Silicon nitride dielectric films are used as etch stops and chemically inert diffusion barriers. Other applications benefit from the relatively high dielectric constant, which allows electrical signals to be rapidly transmitted through a silicon nitride layer. Conventional methods for depositing silicon nitride by chemical vapor deposition work for substrate temperatures more than 250° C. (often much more).
Silicon carbide offers improved performance as an etch stop, diffusion barrier and has a higher dielectric constant. Silicon carbide has been typically used as a substrate for incorporation as active devices but not as a layer deposited on a patterned substrate during formation of semiconducting devices. The cause of this relegation involves the difficulty in etching silicon carbide. The cause may further relate to the typically high deposition substrate temperatures necessary for many prior art silicon carbide chemical vapor deposition techniques. High temperatures, at the very least, may result in diffusion which would degrade electrical characteristics of miniature electrical devices.
Thus, there remains a need in the art for silicon carbide deposition processes appropriate for low deposition substrate temperatures which also offer enhanced control of deposition parameters. This and other needs are addressed in the present application.